3-20 
HYMENOPHYLLACEiE. 
The genus Trichomanes, as restricted by Sir J. E. Smith and 
nearly all modern botanists, appears to depend on “ the cover ” 
consisting “ of one leaf,” and the capillary point of the recep- 
tacle projecting ^‘beyond the cover.” The value of the first of 
these characters appears to me very slight, for it is impossible 
to look at one of the involucres of the present fern without im- 
mediately perceiving that it is composed of two equal parts, 
united by an incrassated suture, which is accompanied through- 
out its length by an external margin or wing ; this is very slen- 
der, and almost obsolete in the Madeira and Killarney plants, 
as already noticed, but strikingly developed in the Glouin Ca- 
ragh plant, as well as in the closely-allied West-Indian Tricho- 
manes alatum^ and several other cognate species. Of the figures 
introduced below, a represents the usual and scarcely varying 
appearance of the Killarney plant, while 5, c, d and e represent 
different states of the Glouin Caragh plant. The other charac- 
ter, the relative length of the involucre and receptacle, seems 
very fallacious, since the development, and even the presence of 
the latter, is very uncertain and irregular. 
a h c d e 
